Apparatus for etching plates in the photo-engraving process.



J. J. C. SMITH.

APPARATUS FOR ETCHING PLATES IN THE PHOTO ENGRAVING PROCESS.

APPLICATION FILED AUG-21,1912- v I Patented Nov. 7, 1916.

2 SHEETS-$HEET I I 1.]. 0. SMITH. APPARATUS'FOR ETCHING PLATES IN THEPHOTO ENGRA-VING PROCESS.

APPLICATION FILED AUG.21. 1912.

1 03,892, Patented Nov. 7, 1916.

2 $HEETS-$HEET 2- o -o o o o doooqo 11 3 o o o o o o 00000 5 0-0 0 o o ocoo o0 JOHN J, G. SMITH, OF PASSAIC, NEW JERSEY, ASSIGNOR TO PAUL M,HAMMALIAN, (3F

I-IACKENSAGK, NEW" JERSEY. V

APPARATUS FOR ETCHING PLATES IN THE PHOTO-ENGRAVING PROCESS.

Specification of Letters Patent.

' Patented Nov. 7, 1916.

Application filed August 21, 1912. Serial No. 716,244.

To all whom it may concern Be it known that I, JOHN J. C. SMITH, a

citizen of the United States, and a resident of Passaic, in the countyof Passaic and State of New Jersey, have invented certain new and usefulImprovements in Apparatus for Etching Plates in the Photo-EngravingProcess; and in order that those skilled in the art may make and use myinvention I give the following specification thereof.

My invention relates to apparatus or machines for applying etchingfluids to platesin the photoengraving process, the plates to be used forprinting purposes as understood in the art, and the object of myinvention is to provide an apparatus of this character which shallaccomplish the etching in a uniform and rapid manner and which apparatusmay be constructed at a relatively low cost.

It may be stated that among the objections to the present methods andapparatus for etching plates by the photoengraving process are (1) theirhigh cost; (2) their lack of uniformity of operation upon the plate,particularly where, as is common, the plates to be etched are ofconsiderable area; (3) the undercutting or widening of the lines of thedesign, and l) the presence of moving parts exposed to the action of thestrongly corrosive etching fluids which tend to rapidly corrode anddeteriorate the same. My invention is designed to overcome these andother objections.

It may be stated that the desiderata in etching plates of the characterdescribed are: (1) rapidity of etching, since for most kinds of work,particularly newspaper work, the plates are required to be preparedwithin a very short time; (2) for good results the etching of the designmust be uniform over the entire surface thereof, and the etching fluidmust be so applied that its action is confined to the lines of thedesign and its tendency to broaden, undercut or widen said lines must beovercome to the greatest extent; (3) low cost of the apparatus and itsmaintenance, and its freedom from injury or destruction by the etchingfluids, These and other advantages are particularly ob tained by myinvention, as will be more par-. ticularly pointed out herein. 7

I have illustrated in the accompanying drawings .a form of apparatusillustrating my'invention, it being understood that said drawings are byway of illustration, and not of limitation, since various modificationscan be made therein without departing from the invention.

In said drawings Figure 1 represents a vertical elevation, parts beingshown in sec-v tion to show the construction. Fig. 2 is a plan view,parts being broken away to show the details of construction. Fig. 3 is aplan view showing the interior of the apparatus and the construction ofthe bottom, parts being broken away to more clearly show details. Fig. lis a transverse sectional view taken on the line X.X, Fig. 3.- Fig. 5 isa detail view showing the plate holder with a plate (partly I brokenaway) supported therein,

, The same reference numerals are applied to corresponding parts in theseveral views.

As illustrated the apparatus comprises a closed tank orreceptacle forthe etching fluid, this tank having a lower part 1, and a cover 2thereon hinged to the lower part, as at 3. The tank, in the apparatusshown, is constructed of hard wood covered-or faced on the side which isto form the interior with celluloid 4. This celluloid in the form ofsheets of suitable thickness is cemented to the wooden pieces formingthe walls, top and bottom of the tank after the manner in which veneeris applied. The pieces forming the walls, top and bottom of thereceptacle are securely fastened together at their joints by celluloidcement, the joints being well coated with the cement and quickly broughttogether under pressure, and so maintained until the cement hashardened. I

, The bottom of the tank has a false or second bottom 5 supported uponparallel strips 6. Both the false bottom 5 and the strips G supportingthe same are of celluloid, the

and. the false bottom 5 cemented thereon. At both ends of the tank thesestrips 6 stop short of the end walls of the tank so as to provide airchests or transverse channels 7, 7, at each end. The longitudinalchannels 6 between the strips 6 all communicate at each end with saidair chests or transverse channels 7, 7. The false or second bottom 5covers these channels and incloses the same forming air ducts asafterward explained. At one end of each of the transverse channels 7,vertical tubes 8, 8 are arranged which communicate at their lower ends,each with one of the transverse channels 7, 7, and at their upper endslead through the wall of the tank where they are connected with branches9, 9, of an air inlet pipe 10, leading from any convenient source of airsupply (not shown). The false bottom 5 is provided over its surface withperforations 11 at frequent intervals, these perforations being situatedover the longitudinal channels 6 formed by the strips 6. The air underpressure from the oppositely disposed pipes 8 is thus led in oppositedirections as indicated by the arrows in Fig. 3 toward the center of thetank where the oppositely directed air-currents communicate orinter-mingle with each other and the perforations are so arranged as todistribute the air issuing therefrom uniformly over the horizontal areaof the tank. The vertical pipes 8 are, in common with all the interiorsurfaces and construction of the tank, formed of celluloid. Theconstruction described is such that air under pressure delivered to thetank by pipe 10 passes through branches 9, 9, tubes 8, 8', to each ofthe air chests or transverse channels 7, T, and is thence distributeduniformly into and throughout the etching fluid in the tank, escapingupwardly through the uniformlyspaced perforations 11 in the false bottom5. The purpose and effect of this will be explained hereinafter.

While I have described the false bottom 5 and the strips 6 supportingthe same as being cemented together and to the bottom of the tank, it isto be understood that the false bottom may be made removable, as forexample by clamps or braces on the sides of the tank, in order to permitof cleaning out of the channels and bottom when necessary.

On the cover 2 of the tank is mounted the mechanism for supporting theplate to be etched in a horizontal position and for giving the same avertically reciprocating movement. This mechanism comprises a base frame12 secured on the top of the cover, in which are mounted verticalstandards 13. At the top of the standards 13 a similar frame 14 isprovided for holding the standards 13 rigidly in proper relation.Between the standards 13 is a cross head 15 arranged to slide up anddown on said standards and to be guided thereby. To the cross head 15 issecured a cross-shaped plunger 16 In order to reciprocate the cross headand v plunger in a vertical direction I provide a lever 25 pivoted to astandard 26 mounted on the cover 2 of the tank. This lever is connectedby a suitable cross piece and links 27 to the cross head so that by anupward and downward movement of the lever 25 the plunger, plate 17, andplate holderhereinafter described, are given a vertically reciprocatingmovement while maintaining the plate horizontally. In order to hold theplunger and plate holder in an upper position without attention on thepart of the op erator,thus keeping the plate out of contact with thefluid in the tank,l provide springs 28 surrounding the standards 13 andbearing against the base frame 12 at one end and the cross head 15 atthe other. Suitable vents 29 are provided in the cover 2 to relieve thepressure of air in the interior of the tank.

The construction of the plate holder is illustrated in Fig. 5 andconsists of a back 19 provided with a series of undercut or T- shapedgrooves 20 in which slide screwclamps 21, 21, having flat and enlargedheads corresponding to the T-shape cross section of said grooves.Holding strips 22, 22 are provided with holes to register with thescrew-clamps 21 in the grooves 20 and r are adjustably secured in placealong said grooves by means of nuts 23. The construction is such that bymeans of the strips 22, which may be adjusted to any position along thegrooves 20, a metal plate or plates to be etched may be secured to theback or holder 19. It will be understood that the strips 22 are undercutto form retaining edges for the plate or plates 2st. As before statedall the interior construction and fit tings including the screw-clamps21 and their nuts 23 are formed of celluloid, and the plunger 16 is alsoprotected with celluloid to resist the action of the etching fluids.

It will be observed that when the tank is said horizontal position andparallel with 1.3-

the plate 5 having the uniformly-spaced perforations 11 throughout theoperation.

The operation of the device is as follows: The apparatus being in alevel position the tank is filled to within three or four inches of thetop of the lower portion 1 with the etching fluid; the plate 2st to beetched is secured on the plate holder 19 by means of the adjustablestrips 22, and the plate holder and plate are slid into the guides 18 onplate 17 at the lower end of the plunger 16. The cover 2 as understoodwill be thrown back on its hinges 3 for this purpose, a handle 30 beingprovided for conveniently lifting the cover. When the plate is securedin position the cover is closed and the air pressure turned on throughthe pipe 10 and branches 9. I have found that an air pres sure of onepound to the square inch is a suitable pressure to employ. The airpassing downwardly from the branches 9 through the tubes 8, 8, entersthe transverse channels 7, 7 at each end of the tank and passes fromthem along the channels 6 between the strips 6 toward the center of thetank as indicated by the arrows, Fig. 3, where the oppositely-directedair currents communicate or intermingle with each other. Air underpressure being thus delivered to channels 6 escapes upwardly through theperforations ll uniformlyspaced in the false bottom 5 and through theetching fluid in the tank. This causes a lively ebullition of theetching. fluid and at the same time mixes air therewith. The plates arethus subjected to the combined action of the uniformlyagitated etchingfluid and of air, which is uniformly distributed throughout the area ofthe tank and is so supplied as to produce substantially uniform airpressure throughout the area of said tank. tion of said fluid is therebyrendered much more rapid, as the corrosive action of the etching fluidon the plate is considerably increased by the presence of the air, andthe constant ebullition ofthe fluid. Such air passing up through theetching fluid from the bottom also keeps the same uniform in strength inall parts, and results in great uniformity in the etching process andthe avoidance of undercut or widened lines in the finished plates. Afterthe cover has been lowered and air turned on as above described thelever 25 is depressed and the plate is brought in contact with thebubbling fluid and may be held there for about half a minute in a steadyposition. The lever is then raised and depressed again in such mannerthat the surface of the plate to be etched is sharply dashed into andout of the bubbling fluid. This operation may be kept up at shortintervals for about anninute when the plate may be examined by raisingthe cover to observe the progress of the The acetching. This operationmay be repeated as often as necessary to obtain the desired depth oflines. Practice and ordinary skill and observation will soon enable theoperator to obtain the best results. For some plates, such as copperplates, it is not essential to give the same the upwardand downwardmovement; but such plates may be held steady in contact with thebubbling fluid. The agitation of the fluid in contact with the plate notonly considerably .increases the rapidity of the action of the fluid butat the same time assists in removing and washing out the oxid formed inthe lines, and the dashing movement of the plate up and down against thefluid further increases the action of the fluid and the washing outeffect. The result is a very rapid and uniform etching of the plate.

lVhile I have described in detail the various features of the inventionit will be understood that the same may be modified and changed withoutdeparting from the principles of the invention.

What I claim is:

1. An apparatus for applying etching fluids to plates, having incombination a tank for the etching fluid, means in said tank fordischarging and uniformly distributing ainthroughout the body of thefluid in said tank, said means comprising a series of air ducts arrangedin the bottom of the tank, each of said air ducts having a plurality ofdischarge openings along its length, said openings being submerged inthe fluid in the tank, air chests at the opposite ends of sald air ductslnto whlch each of said ducts opens, means for suplymg air under pres- 1sure to said air chests, means for supporting spaces, transverse airpassages beneath said false bottom at each end of said strips andcommunicating with each of the air passages between said strips, meansfor delivering air to said transverse air passages, a plate holdersupported in saidtank for holding the plate to be etched substantiallyparallel with the level of fluid in said tank and means for moving saidplate holder into and out of the liquid in the tank.

3. .An apparatus for applying etching fluid to plates, having an airdistributing plate that is provided wi llllniformly spaced openings,channels communicating with said openings and passages for supplying opposed currents of air to said channels.

JOHN J'. G. SMITH.

\Vitnesses HENRY C. YVORKMAN, Var. A. COURTLAND.

openings, means for supplying equal proportions of air to said openingsand means for supporting a plate in proximity to said air distributingplate.

4. An apparatus for applying etching fluid to plates, having an airdistributing plate that is provided with uniformly spaced Copies of thispatent may be obtained for five cents each, by addressing theCommissioner of latents, Vfeshington, D. C.

